Length-sorted semiconducting carbon nanotubes for high-mobility thin film transistors

Abstract

We have developed a process for chemical purification of carbon nanotubes for solution-processable thin-film transistors (TFTs) having high mobility. Films of the purified carbon nanotubes fabricated by simple drop coating showed carrier mobilities as high as 164 cm 2 V -1 s -1 , normalized transconductances of 0.78 Sm -1 , and on/off current ratios of 10 6 . Such high performance requires the preparation of a suspension of micrometer-long and highly purified semiconducting single-walled carbon nanotubes (SWCNTs). Our purification process includes length and electronic-type selective trapping of SWCNTs using recycling gel filtration with a mixture of surfactants. The results provide an important milestone toward printed high-speed and large-area electronics with roll-to-roll and ink-jet device fabrication.

Large-scale complementary macroelectronics using hybrid integration of carbon nanotubes and IGZO thin-film transistors

“…On the other hand, carbon nanotube network thin film has emerged as a potential building block for macroelectronics such as backpanel organic light-emitting diode pixel-driving circuits for active-matrix flat-panel displays 17,18 , digital circuits [19][20][21][22][23][24][25][26][27] , radio frequency identification tags 28 , sensors [29][30][31] and memories 32 . CNT network TFTs exhibit the merits of high transparency, high flexibility, low process cost, low processing temperature and high scalability, while traditional TFT materials such as amorphous silicon and polycrystalline silicon are usually not transparent, have poor flexibility, require high processing cost and use high processing temperature 20,23,[33][34][35][36][37][38][39] . However, semiconducting CNTs are usually p-type semiconducting materials in atmosphere due to adsorption of oxygen [40][41][42] , and techniques to convert CNTs to n-type semiconductors 22,41,[43][44][45][46][47][48][49] still require further development to achieve long-term stability (for example, over multiple years), and sometimes bear significant device-todevice variation 22,46,49 .…”

High performance transistors via aligned polyfluorene-sorted carbon nanotubes

“…24,25 The on-and off-conductance normalized to width for each device and varying channel lengths of 0.4, 1, 2, 3, 4, and 9 lm are plotted in Figure 2 Figure 3 with the performance state-of-the-art s-SWCNT FETs from literature. 11,14,24,25,[34][35][36][37][38] On-conductance as high as 240 lS lm À1 have been reported for SWCNT FETs in the direct transport regime; however, the on/off ratio in such devices was limited to 10 3 presumably by the presence of metallic nanotubes. Similarly, in the percolative regime, high on/off ratios on the order of 10 7 have been achieved, but devices were limited by an on-conductance of 4 lS lm À1 for channel length of >5 lm.…”

“…Median values for this work are plotted as red stars and calculated from the following number of devices at each channel length: 400 nm (22 devices), 1-2 lm (6 devices), 3-4 lm (6 devices), and 9 lm (4 devices). Error bars for this work indicate maximum and minimum values (Sangwan, 14 Engel, 25 Miyata, 36 Kang, 37 Jin, 35 Cao, 24 Sun, 11 Wu, 34 and Kim, 38 respectively).…”

Length dependent performance of single-wall carbon nanotube thin film transistors

“…This result suggests that the performance potential of SWCNT-TFTs can be predicted from the average length of SWCNTs. Therefore, for the fabrication of high performance SWCNT-TFTs, it is important to increase the average length of SWCNTs by extracting long SWCNTs or eliminating short SWCNTs from SWCNT dispersions, even for high purity semiconducting SWCNTs [25].…”